Heparin, a highly sulfated heparin-like glycosaminoglycan (HLGAG) produced by mast cells and isolated from natural sources, is a widely used clinical anticoagulant. However, the effects of natural, or unfractionated, heparin can be difficult to predict and patients must be monitored closely to prevent over- or under-anticoagulation. Low molecular weight heparins (LMWHs) obtained by various methods of fractionation or depolymerization of polymeric heparin have more predictable pharmacological action as anticoagulants, reduced side effects, sustained antithrombotic activity, and better bioavailability than unfractionated heparin (UFH). Several LMWHs are approved for outpatient treatment of thrombotic conditions.
There is increasing interest in the potential role of antithrombotic agents in the management of cancer patients. Results from several recent clinical trials have suggested a survival advantage for certain types of cancer patients treated with LMWHs (reviewed in Lemoine, 2005, Journal of Clinical Oncology, 23: 2119-20).